bisecting fixing commit since 01364dad1d4577e27a57729d41053f661bb8a5b9 building syzkaller on 78267cec1aaa5e066d66e6a6c76fea1753e51b46 testing commit 01364dad1d4577e27a57729d41053f661bb8a5b9 with gcc (GCC) 8.1.0 kernel signature: 6114d3874770e3c6cde6dc1a081c7c75c092bc95ddd9382cd4bb84db56dba74e all runs: crashed: KASAN: use-after-free Read in snd_seq_timer_interrupt testing current HEAD a41ba30d9df20fe141c92aacbb56b6b077f19716 testing commit a41ba30d9df20fe141c92aacbb56b6b077f19716 with gcc (GCC) 8.1.0 kernel signature: 8bc62d291695f728ff0ad09a6ace37309ea1ec1d17bf385580a3b83569fd37d1 all runs: crashed: KASAN: use-after-free Read in snd_seq_timer_interrupt revisions tested: 2, total time: 23m46.275349658s (build: 17m4.582133521s, test: 6m8.493122547s) the crash still happens on HEAD commit msg: Linux 4.14.181 crash: KASAN: use-after-free Read in snd_seq_timer_interrupt batman_adv: batadv0: Interface activated: batadv_slave_1 IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready ================================================================== BUG: KASAN: use-after-free in snd_seq_timer_interrupt+0x2eb/0x3b0 sound/core/seq/seq_timer.c:145 Read of size 8 at addr ffff8880a891c118 by task syz-executor.5/6494 CPU: 0 PID: 6494 Comm: syz-executor.5 Not tainted 4.14.181-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 print_address_description.cold.7+0x9/0x1c9 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report.cold.8+0x11a/0x2d3 mm/kasan/report.c:409 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 snd_seq_timer_interrupt+0x2eb/0x3b0 sound/core/seq/seq_timer.c:145 snd_timer_interrupt+0x617/0x1080 sound/core/timer.c:869 snd_timer_s_function+0xae/0x130 sound/core/timer.c:1105 call_timer_fn+0x142/0x570 kernel/time/timer.c:1279 expire_timers kernel/time/timer.c:1318 [inline] __run_timers kernel/time/timer.c:1636 [inline] run_timer_softirq+0xc99/0x1210 kernel/time/timer.c:1649 __do_softirq+0x246/0x9b0 kernel/softirq.c:288 invoke_softirq kernel/softirq.c:368 [inline] irq_exit+0x15f/0x1a0 kernel/softirq.c:409 exiting_irq arch/x86/include/asm/apic.h:648 [inline] smp_apic_timer_interrupt+0x149/0x5d0 arch/x86/kernel/apic/apic.c:1102 apic_timer_interrupt+0x9a/0xa0 arch/x86/entry/entry_64.S:793 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline] RIP: 0010:lock_release+0x449/0x830 kernel/locking/lockdep.c:4020 RSP: 0018:ffff888093f77be0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10 RAX: dffffc0000000000 RBX: 1ffff110127eef80 RCX: 1ffff11010bd055f RDX: 1ffffffff0fe2cc9 RSI: 0000000000000002 RDI: 0000000000000286 RBP: ffff888093f77c88 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000028 R11: ffff888085e82280 R12: ffff888085e82280 R13: 205a6e236c4567aa R14: 0000000000000001 R15: ffff888085e82280 __raw_spin_unlock include/linux/spinlock_api_smp.h:150 [inline] _raw_spin_unlock+0x1a/0x50 kernel/locking/spinlock.c:184 spin_unlock include/linux/spinlock.h:357 [inline] evict+0x367/0x590 fs/inode.c:570 iput_final fs/inode.c:1524 [inline] iput+0x3ac/0x810 fs/inode.c:1551 do_unlinkat+0x457/0x650 fs/namei.c:4098 SYSC_unlink fs/namei.c:4139 [inline] SyS_unlink+0x11/0x20 fs/namei.c:4137 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45c597 RSP: 002b:00007fffa93c5588 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045c597 RDX: 00007fffa93c55a0 RSI: 00007fffa93c55a0 RDI: 00007fffa93c5630 RBP: 000000000000009d R08: 0000000000000000 R09: 000000000000000f R10: 000000000000000a R11: 0000000000000246 R12: 00007fffa93c66c0 R13: 0000000000e36940 R14: 0000000000000000 R15: 00007fffa93c66c0 Allocated by task 9447: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x152/0x7a0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] queue_new sound/core/seq/seq_queue.c:113 [inline] snd_seq_queue_alloc+0x51/0x480 sound/core/seq/seq_queue.c:195 snd_seq_ioctl_create_queue+0xa8/0x2d0 sound/core/seq/seq_clientmgr.c:1528 snd_seq_ioctl+0x1b7/0x380 sound/core/seq/seq_clientmgr.c:2144 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 9444: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 queue_delete+0x8b/0xa0 sound/core/seq/seq_queue.c:156 snd_seq_queue_client_leave+0x27/0x100 sound/core/seq/seq_queue.c:604 seq_free_client1.part.9+0xef/0x260 sound/core/seq/seq_clientmgr.c:263 seq_free_client1 sound/core/seq/seq_clientmgr.c:256 [inline] seq_free_client+0x5c/0xd0 sound/core/seq/seq_clientmgr.c:285 snd_seq_release+0x48/0xe0 sound/core/seq/seq_clientmgr.c:367 __fput+0x232/0x750 fs/file_table.c:210 ____fput+0x9/0x10 fs/file_table.c:244 task_work_run+0xe5/0x170 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x16a/0x1b0 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x416/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8880a891c0c0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 88 bytes inside of 512-byte region [ffff8880a891c0c0, ffff8880a891c2c0) The buggy address belongs to the page: page:ffffea0002a24700 count:1 mapcount:0 mapping:ffff8880a891c0c0 index:0xffff8880a891cd40 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffff8880a891c0c0 ffff8880a891cd40 0000000100000005 raw: ffffea0002277560 ffffea00022a3d60 ffff8880aa800940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a891c000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a891c080: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >ffff8880a891c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a891c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a891c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================